6285-57-0

333-20-0

100-01-6

6285-57-0

GENERAL METHOD: A solution of 4-nitroaniline (2 mmol) in acetonitrile (15 ml) was slowly added to a solution of potassium thiocyanate (8 mmol) in acetonitrile (15 ml). Subsequently, 0.06 g (30 mol%) of BF3/SiO2 nanocatalyst was added to the reaction system and the mixture was placed in an ice salt bath and mechanically stirred for 30 min. A solution of bromine (4 mmol, 0.2 ml) in acetonitrile (3 ml) was slowly added through a dropping funnel, and the dropping rate was controlled to ensure that the reaction temperature did not exceed 0 °C. After the addition of the bromine solution, the reaction continued to be stirred at room temperature for 4 h, during which the progress of the reaction was monitored by TLC. Upon completion of the reaction, the reaction mixture was poured into water, heated in a 70 °C water bath and thermally filtered to remove the catalyst. The catalyst was washed with acetone and recycled for reuse. The filtrate was neutralized to neutrality with 10% NaOH solution and the precipitated solid was collected by filtration, dried and recrystallized with ethanol (10 ml) to give the target product 2-amino-6-nitrobenzothiazole. The structure of the product was confirmed by the following physical and spectral data and verified by comparison with standards. Spectral data of 2-amino-6-nitrobenzothiazole: yellow solid; yield = 93%; melting point = 202-204 °C (literature value 203 °C); FT-IR (KBr, cm^-1): 3315, 3012, 2835, 1580, 1476, 1261, 920, 742, 512; ^1H NMR (400 MHz, CDCl3 , δ ppm): 5.44 (s, 2H, NH2), 7.4-7.5 (d, 2H, Ar-H), 7.71 (s, 1H, Ar-H); ^13C NMR (100 MHz, DMSO-d6, δ ppm): 119, 120.9, 125.15, 126.07, 133.1, 152.15, 167.75.